Last summer, Todd and Andrea Beauchamp got a nasty surprise when the utility bill for their newly rented Los Angeles house came in at nearly triple what it was for their previous place.

"We were shocked," says Andrea Beauchamp. "The bill was over $800, which was way more than we had budgeted for."

Their previous place, a slightly smaller house a mile away, didn't have a pool. But the Beauchamps knew that a pool could be a real power drain, so they chose not to heat it. What they didn't know was just how energy inefficient the rest of their new house was. If they had known, they say, they never would have signed the lease.

Several apartment managers say the Beauchamps could have asked their landlord to request a utility bill from the previous tenant. But that's not always practical. And even if renters and buyers can get the previous tenant's bill, it's not necessarily the best way to gauge energy efficiency because power costs also reflect the occupants' own consumption habits, says Liz Robinson, president of the Keystone Energy Efficiency Alliance, a Philadelphia nonprofit that coordinates local utilities and businesses throughout Pennsylvania.

"The best way to think about energy in our homes is to think of how we measure a car's efficiency through the miles-per-gallon metric," says Robinson. "What buyers and renters need is an easy-to-understand number that tells them how the place they're at looking at stacks up against other options on the market."

More On Energy Efficiency:

Two tools coming online

Right now, the closest thing we have to mpg for the home is the Home Energy Score, or HES. Developed by the U.S. Department of Energy, or DOE, the HES rates a building's efficiency against similar buildings in the same climate zone. The HES works on a 1-10 scale, with 10 being the best. So far, about 30 states have begun pilot programs to implement the HES, according to Robinson. But while she describes the rate of implementation as "very rapid," it's still up to each utility district to decide whether to adopt the HES.

"The great thing about the HES is that it's easy to understand, so you know that a home that's an 8 or 9 is better than a 5, and that you don't want to buy or rent a place that's a 2 because the energy costs will be higher," says Robinson. "But it won't tell you what your power bill will be because that also depends on you."

Even the most efficient buildings can have high energy costs if the occupants are wasteful. So for that reason, Robinson is also a proponent of a DOE tool known as the Green Button, which allows current rate payers to log in to their account on the utility's website and get a detailed breakdown of their energy use.

"The Green Button is more focused on helping consumers adjust their behavior to save money," Robinson says. "But as the Green Button enters wider use, I think we'll see homebuyers and renters asking for that information so they can look at it in conjunction with the HES."

Like HES, the Green Button's availability varies by utility district.

In the meantime

Buyers and renters who live in areas that haven't yet adopted the Green Button or the HES aren't without options.

"The best way to estimate your home's energy efficiency is to do a home energy audit," says Neal Humphrey, a building expert with Alliance to Save Energy, a Washington, D.C., nonprofit that promotes energy efficiency through research, education and advocacy. "Many utility companies offer free or subsidized audits, which are the best way to zero in on things like poor insulation and leaks around windows and doors that can drive up energy costs."

Unfortunately, audits are geared toward suggesting improvements, which make them ideal for homeowners but not necessarily useful for renters. And if the utility doesn't subsidize the audit, the consumer may have to pay as much as $500 to a private auditor, which could be too much of a cost for most renters, but well worth it for a buyer.

Slightly less accurate than an audit -- but still useful -- are tools like Home Energy Saver, an online application developed by the U.S. Department of Energy to help consumers estimate their building's efficiency themselves.

"It's a streamlined version of professional audit software, but it can tell you a lot about your building and where you're least efficient," says Humphrey, adding that the process can take between 10 minutes to an hour, depending on how thorough you want to be.

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